placeholder not working properly in firefox

Question

I am aware that older firefox doesn't support placeholder. But my firefox is up-to-date and I can see placeholder on this page: http://www.dzyngiri.com/demo/flat-ui-login-form/. But I cant see the placeholder when I open my codes. Mine DOES show up if I use chrome or IE

    <form id="Signup">
        <input type="text" placeholder="username" id='name' size="15px"><br>
        <input type="password" placeholder="password" id='pw' size="10px"><br>
         <input type="password" placeholder="retype-password" id='confirmPw' size="10px"><br>
        <input type="text" placeholder="email" id='email' size="10px"><br>

Answer 1

If you're up for JS solution, it covers all browsers.

<input name="username" type="text" value="Username" onfocus="if(this.value==this.defaultValue)this.value='';" onblur="if(this.value=='')this.value=this.defaultValue;">